(1) Field of the Invention
The present invention concerns a system for adjusting the working range of a damper clutch in an automatic transmission of a vehicle according to the load applied to the engine and the driving habit of a driver.
(2) Description of the Prior Art
Generally, the automatic transmission suffers an inferior fuel consumption rate, which is about 10% lower than that of the manual transmission, because the power of the engine is indirectly transmitted by means of a hydraulic pressure. Namely, the power loss is caused by the fluid slip of the torque converter in about 70%, mechanical drive in about 15%, and the slip of the clutch and band in the remaining part. The damper clutch is used to directly connect the pump of the torque converter with the turbine above a given vehicle speed in order to reduce the power loss due to the fluid slip, thus improving the fuel consumption rate as well as quietness.
The working range of the damper clutch is conventionally set with reference to the throttle valve position and the rpm (revolution per minute) of the engine. Especially, when the damper clutch is set to work in a lower shift phase, it works always from the lower shift phase regardless of the engine load. However, in this case, the acceleration of the vehicle becomes less effective because of the damper clutch directly connecting the pump of the torque converter with the turbine. Additionally, if the working range of the damper clutch is set to be wide without considering the engine load caused by various systems equipped in the vehicle, the drive capability may be deteriorated.